Diagnosis System

1. The vehicle's ECU uses the ISO 9141-2 for communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
   Fig 1: Identifying DLC3 Connector Terminals

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   DLC3 REFERENCE
   
   

   Symbols (Terminal No.)	Terminal Description	Condition	Specified Condition
   SIL (7) - SG (5)	Bus + line	During transmission	Pulse generation
   CG (4) - Body ground	Chassis ground	Always	Below 1 Ω
   BAT (16) - Body ground	Battery positive	Always	11 to 14 V

   If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.

   HINT:

   Connect the cable of the intelligent tester to the DLC3, turn the ignition switch ON and attempt to use the tester. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the tester.

   • If communication is normal when the tester is connected to another vehicle, inspect the DLC3 of the original vehicle.
   • If communication is still not possible when the tester is connected to another vehicle, the problem may be in the tester itself. Consult the Service Department listed in the tester's instruction manual.

HINT:

The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. A simulation of the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.

1. Vibration method (When vibration seems to be the major cause)

   HINT:

   Perform the simulation method only during the primary check period (for approximately 6 seconds after the ignition switch is turned to the ON position).

   1. Slightly vibrate the part of the sensor considered to be the cause of the problem with your fingers and check whether the malfunction occurs.

      HINT:

      Shaking the relays too strongly may result in open relays.

   2. Slightly shake the connector vertically and horizontally.
   3. Slightly shake the wire harness vertically and horizontally.

      HINT:

      The connector joint and fulcrum of the vibration are the main areas that should be checked thoroughly.

Fig 2: Identifying Simulation (Vibration Method)

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1. Initial check
   1. Turn the ignition switch ON.
   2. The passenger airbag ON / OFF indicator illuminates ON and OFF for approximately 4 seconds, and then turns them off for approximately 2 seconds.
   3. Approximately 6 seconds after the ignition switch is turned to the ON position, the passenger airbag ON / OFF indicator indicates ON or OFF depending on the conditions listed below.
      PASSENGER AIRBAG ON / OFF INDICATOR
      
      

      Front Seat Passenger	ON Indicator	OFF Indicator	SRS Warning Light
      Adult seated	ON	OFF	OFF
      Child seated / Child restraint system set	OFF	ON	OFF
      Vacant	OFF	OFF	OFF
      Passenger occupant classification system failure	OFF	ON	ON

   HINT:

   • The passenger airbag ON / OFF indicator operates based on Fig 3 in order to check the indicator light circuit.
     Fig 3: Identifying Passenger Airbag ON/OFF Indicator Position Blinking Pattern

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   • When the occupant classification system malfunctions, the SRS warning light comes on and the passenger airbag ON / OFF indicator indicates OFF. In this case, check the DTCs in the airbag system first.

1. Turn the ignition switch ON.
2. Check that the passenger airbag ON / OFF indicator illuminates ON and OFF for approximately 4 seconds, and then turns them off for approximately 2 seconds.

   HINT:

   Refer to Fig 4 in the previous step regarding the passenger airbag ON / OFF indicator when approximately 6 seconds have elapsed after the ignition switch is turned ON.

   Fig 4: Identifying Passenger Airbag ON/OFF Indicator

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002